Price is the result of the subjective valuations of the exchangers.  One good is being exchanged for another.  The exchangers must have expected to profit from the exchange.  If not, the exchange never would have been made.  The goods are valued by the individuals according to the usefulness to them.  A third party doesn’t designate what individuals are to value something.  Price is a ratio of a good.

The subjective value must be measured by its marginal utility.  If someone makes fishing poles, he can’t trade half of it for a piece of fish.  The fishing pole would be useless, and the trade wouldn’t be made.  He could give him two fish to complete the trade.  However, the fishing pole maker only wants one fish and the other one will quickly spoil.  Fish doesn’t make a good medium of exchange.  They’ve encountered a barrier to indirect exchange. 

A medium of exchange must have certain qualities.  Fish wouldn’t maintain its purchasing power.  Fish isn’t durable.  Other than durable, money must also be: valuable, high value to weight ratio, scarce, recognizable, divisible, and fungible.  The first medium of exchange probably didn’t satisfy all of these.  It must satisfy this criterion if one is to remain in use for an extended period of time.

Exchanges made with the use of a medium is determined by a ratio.  The ratio could be determined by a specific weight.  The ratio on the exchange has influence over future exchanges.  Don’t confuse this as objective value.  It just provides a basis for the seller.  The ratios used today are linked with yesterday and tomorrow.  The trade is still based on the subjective value of the purchaser.

This is why money printing doesn’t make anyone richer.  More of the medium of exchange is in circulation.  This will make the purchasing power of money fall.  Of course, it doesn’t effect everyone equally.  There would be no reason to do it if it did.  The early receivers benefit at the expense of the late receivers.  If money printing did make people richer.  Why are there any poor countries or people in the world?

References

Ludwig von Mises; The Theory of Money and Credit

Michael DeVinney; Pure Political Philosophy